An ocean current is "any more or less permanent or continuous, directed movement of ocean water that flows in one of the Earth's oceans," according to ScienceDaily.com. Currents are created by a variety of forces.
Forces which generate currents include the rotation of the earth, the rotation of the wind, the temperature, salinity differences and the gravitational pull of the moon. Depth contours, the shoreline and other currents influence a current's direction and strength. Ocean currents can flow for thousands of kilometers and help to determine the climate of the continents, especially in regions that border the ocean, ScienceDaily.com states.
The Gulf Stream provides a dramatic example of a current, making northwest Europe significantly more temperate than other regions at the same latitude.